1. There is one supplier, so you have no choice. 2. Even if you had a choice to sign the contract, this still means that it's not the same as a trade-in, because trade-ins are always voluntary, but once you have signed the contract, a right of first refusal is not.

In general, the "you chose to sign the contract" argument is a poor justification for bad contracts. If the contract is bad, it is bad regardless of whether you chose to sign it.